Harold m



H. M. MARTIN.

PROC ESS AND APPARATUS FOR TREATING STORAGEBATTERY PLATES. APPLICATION FILED N0v,'14.19|4'.

- 1,310,871. Patented July 22, 1919.

Attest: I Inviggtor: y 41mm. a

HAROLD M. MARTIN, NEW YORK, N. Y., ASSIGNOR TO PHILADELPHIA STORAGE BATTERY COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION.

PROCESS AND APPARATUS FOR TREATING STORAGE-BATTERY PLATES.

a citizen of the United States, residing at New York city, in the county'of New York and State-of New York, have invented certain new and useful Improvem nts in Processes and Apparatus for Treating Storage- Battery Plates, fully described and represented in the following specification and the accompanying drawings, forming a part of the same. p

This invention relates to the manufacture of storage-battery plates, and ccmprisesa tive plates, wherein the negative plates in charged or active condition, that is, with the active materialof the plates in the metallic state, are dried in an atmosphere of a gas which is chemically inert with respect to the active material of the plate in it's metallic state- The invention comprises further an apparatus for carrying outor practising the process.

After the active material of a negative plate of a storage battery. has been reduced to the metallic state by the initial or any subsequent charging passage of the electric current, withdrawal of the negative plate from the electrolytic solution and exposure to air will result ina substantial oxidizing of the active material so that when subsequently immersed in the electrolyte with suitable positive plates recharging is pra'ctically necessary. In order to maintain the plates in condition for efiicient discharge, therefore, it is customary and necessary in the absence of special treatment of the nega tive plates that they shall be kept immersed in the acid or other electrolytic solution. This necessity of keeping the negative plates immersed to prevent access of air thereto has various objections, such asthe increased difliculty and cost of transportation, and furthermore, with the usual lead filled plates the battery after charging will gradually lose its charge and the plates will in time become impaired through the formation of sulfate of lead.

The object of the present invention is to avoid the necessity of keeping the negative plates of storage batteries immersed by drying the plates without changing the condi- Speeification of Letters Patent.

Patented July 22, ieie.

Application filed November 14, 1914. Serial No. 872,092.

tures. Negative plates so dried may be readil y transported and kept for long periods of time w1thout change from the condition in which they will provide with suitable positive plates in the proper condition a so i called charged cell for supplying electrical energy. With this object in view, negative storage battery plates with the active material in the charged or metallic .state have been dried by heating in a partial vacuum; but this method of drying has the disadvantages that because of the practical impossibility of obtaining an absolute vacuum in process of producing potentially active negaoperating on a comme pial scale the active material of the plates oxidizes to such an appreciable extent during the drying process as to materially reduce its discharging eificiency, and that the supplying of heat to the plates during the drying in partial vacuum is a matter of some difficulty and requires a comparatively expensive and cumbersome apparatus since the application of heat to the plates must be by contact. My invention avoids thedisadvantages of the vacuum drying process and ,makes it possible to dry the plates qu1ckly and with practically no oxidation of the active material and'with,

the use of a comparatively simple and inexpensive apparatus.

In preparing the negative plates inaccordance with my process, after being charged, or having their active material reduced to the metallic state, that is, in the or dry, that is, a gas which is chemically inert with respect to the .active material when in either a wet or dry state. With lead filled plates, I have used hydrogen gas,

nitrogen has practical advantages for commercial use, and other inert gases such as carbon dioxid would apparently meet the requirements. When the plates have been charged in a liquid containing sulfuric acid or other substance which if left in the plate would hinder or prevent thorough drying, the plates should be thoroughly washed in water before drying. The gas in which the plates are dried should most desirably be caused to move past the plates and should of course be in a suitable dry condition, and

to expedite the drying operation the drying gas may be, and most desirably is, heated to a suitable temperature which should of process and embodying the apparatus feacourse not be high enough to aifect any of the substances comprised in the plate. If a heated gas is employed, the plates should be cooled beforebeing removed from the gas so as to avoid access of air to the plates While hot, thus avoiding oxidation which would result from the action of the oxygen of the-air on the hot metallic lead or other active material of the plates.

An apparatus suitable for carrying out the tures of the invention is illustrated diagrammatically in the accompanying drawing.

)Referring to the drawing, the apparatus I shown is intended for drying with a stable gas and comprises an airtight drying chamber 10 provided by a suitable casing having a suitably arranged door 11 through which the plates to be dried may be introduced into and taken from the chamber. The chamber is provided with an inlet 12 .for the supply of the inert drying gas, and with anoutlet 13 for escape of the displaced air and thereafter of the drying gas so that a movement of the gas through the chamber may be maintained. For economy'in the use of the gas, the outlet 13 is connected outside'the chamher with the 'inlet 12 by a circulationpipe 14 so that the gas may be causedto circulate continuously through the chamber and through the pipe 14. Interposed in the pip 14 is a drier 15 which may be formed as shown by a cooling and condensing chamber provided with a cooling coil 16, and between the cooler and the inlet 12 is connected a heater 17 which may be formed as shown by a chamber containing a steam orother heating coil 18. Circulation may be maintained in'any suitable manner but usually it will be most desirable to connect in the pipe 14 a suitable pump 20 as shown. An inlet pipe 21 leads into the pipe 14 on one, side of the ratus shown, the plates to be dried are placed I in the chamber 10, being supported therein by suitable boxes and racks or other means whereby the plates are caused to stand separated from each other so as to permit a free circulation of the drying gas past them and in contact with the surface of their active material. The door of the chamber being then closed, the air in the drying. chamber and in the other portions of the circulation system is displaced by the drying gas introduced through the inlet 21, the air escaping through the outlet 22. When the air has; all been displaced so that the atmosphere within the system. consists only of the hydrogen or nitrogen or other stable inert gas used,.

the inlet/21 and-outlet are closed and the circulating pump 20 1s put into operation. The is heated in passing through the heater 17 before entering the drying cham- 'coil 18, but the circulation of the gas is thereafter continued until the temperature of the plates has been reduced to practicallymormal atmospheric temperature. The dried plates may be removed from the drying chamber. I The cessation of the passage of water from the drip pipe 25 will indicate that the plates are-dry.

Batteries made up with negative plates treated or prepared according to my process may be. allowed to stand for a long period and be at all times ready for discharge on.

ap lication of the electrolyte, and the prepared negative plates may equally well, of course, be kept without beingmade up in batteries, lasting without deterioration. The plates should be kept free from moisture and from access of an unduly damp atmosphere.

I believe that the period during which the plates will retain their properties and be ready for use in batteries without recharging is practically unlimited provided'they are kept absolutely dry and free from access of any moisture.

It will be understood that the invention considered either as a process or an apparatus invention is not to be limited to, or to the use of, the exact form of apparatus shown.

What is claimed is: 1 p

1. The'process of preparing potentially active negativestorage battery plates which comprises drying the active material of such plates in an atmosphere of a heated gas inert to said material in its metallic state; and cooling the .material before exposing the plates to air.

I 2. The process of dryingv negative storage battery plates having their active material in the metallic state, which comprises subjecting said plates to the drying action of a moving atmosphere of a gas inertwith respect to such active material; repeatedly heating saidgas and thereafter subjecting the plates to its action; and finally subjecting the plates to cooled gas before exposing them to the air.

3. The process of drying negative storage.- battery plates having their active material in the metallic state, which comprises subje-ctlng the plates to the drying action of a gas inert with respect to such active Ina-- tcrial; cooling the gas to condense the moisture therefrom; heating the gas; causing. the hot gas to further act on the plates; and finally subjecting the plates to the action of cooled gas before exposing them to the air.

4. The process of drying negative storage battery plates having their active material in the metallic state, Which comprises the circulation over. said plates of heated gas inert'with respect to such active material until the moisture is substantially removed therefrom; and thereafter circulating cooled inert gas over the plates until their temperature is reduced substantially to atmospheric normal.

5. The process of drylng negative storage battery plates having their active material in a metallic state which consists in heating a body of gas inert tothe active material of said plates; passing said heated gas over the plates to remove the moisture therefrom;

cooling the gas to remove the moisture carried by it; reheating the gas and so on, until the plates are dry. p

6. The process of drying negative storage 1 battery plates having their active material in a metallic state which consists in heating-a body of gas inert to the active material of said plates; passlngsald heated gas over the plates to remove the moisture therefrom;

coollng the gas to remove the moisture earried by it; reheating the gas and so on until the plates'are dry; and thereafter continu HAROLD M. MARTIN.

l/Vitnesses f A. L KENT, PAUL H. FRANKE. 

